1. Field of the Invention
The invention relates to a deflection fitting for a safety belt, especially for motor vehicles, with a fitting plate which can swivel about a swivel axis and which has a guide slot defined by a rounded deflection surface and lateral edge webs adjacent thereto, with the guide slot arranged asymmetrically to the swivel axis with regard to its lengthwise dimension.
2. Description of the Prior Art
The deflection fittings used in practice are designed to be symmetrical, with respect to the arrangement of the swivel axis, i.e. the support hole at which the fitting plate is fastened, for instance, to the frame of a motor vehicle in a rotatable manner, relative to the lengthwise dimension of the guide slot in which the safety belt runs, so that the deflection fittings can be used for right-hand and left-hand installations. When the belt is pulled out as well as during return of the belt, the fitting plate adjust itself at an angle which results in the following difficulties in practice: when the belt is pulled out, it runs in the travel direction upward along the guide slot and in this manner comes into contact with the lateral outer web, which defines the guide slot, of the fitting plate. Consequently, friction forces result which lead to heavy transversal stress of the belt and therefore to damage or wear thereof. A similar action happens upon return of the belt in the reverse manner on the opposite boundary of the guide slot. Not of least importance, the wearing comfort of the belt system is greatly impaired due to these friction forces, since according to these friction forces, the forces to be supplied for pulling-out and reeling-in the belt must be correspondingly large. If a load is applied to the system, i.e. in the case of a crash, a further disadvantage occurs in the case of symmetrical design, namely, that after the belt is blocked, a certain amount of pull-out of the belt takes place, in the process of which the heavily loaded belt is displaced laterally upward in the guide slot of the stationary fitting and is squeezed there, which can lead to a break of the belt in the case of very high loadings.
While it has been attempted to correct these disadvantages by an asymmetrical arrangement of the mounting hole, i.e. of the swivel axis relative to the longitudinal dimension of the guide slot (German Published Non-Prosecuted Application No. 24 28 814), the swivel axis in this known arrangement is arranged asymmetrically relative to the guide slot against the travel direction. Tests have shown that with normal handling and in particular in case of a crash load, the belt has a tendency even more than with a symmetrical arrangement to run up on a confining edge, i.e. on the edge web of the fitting plate, so that this design turned out to be unusable and has not found practical application.